a. Field of the Invention
This invention relates to introducers for inserting and guiding medical devices within a body. In particular, the instant invention relates to an introducer sheath configured to allow electric currents generated by body electrical activity or sources external to the body to pass through the sheath and/or to a medical device contained therein.
b. Background Art
A wide variety of medical devices are inserted into the body to diagnose and treat various medical conditions. Catheters, for example, are used to perform a variety of tasks within human bodies and other bodies including the delivery of medicine and fluids, the removal of bodily fluids and the transport of surgical tools and instruments. In the diagnosis and treatment of atrial fibrillation, for example, catheters may be used to deliver electrodes to the heart for electrophysiological mapping of the surface of the heart and to deliver ablative energy to the surface among other tasks. Catheters are typically routed to a region of interest through the body's vascular system. In a conventional approach, an introducer is used to puncture the skin surface and a sheath having an inner diameter greater than the outer diameter of the catheter is threaded through the vasculature to a region of interest. The catheter is then moved longitudinally through the sheath to the region of interest either manually by a clinician or through the use of electromechanical drive systems.
Conventional introducer sheaths are constructed from electrically insulating materials which prevent electric currents from penetrating the sheath and reaching the catheter. As a result, it is not possible for electrodes on the catheter to measure electrical activity (i.e. electrograms) from surrounding tissues while in the sheath even though this information may be relevant to diagnosis or treatment. Medical device positioning systems may also rely on signals generated by catheter electrodes in response to externally generated electric fields to determine the position of the catheter and guide the catheter to a target location. Because conventional sheaths prevent electric currents from reaching the electrodes, the position of the catheter electrodes within the sheath cannot be directly monitored and incorrect position information may be generated. This deficiency is especially problematic when the catheter is used as a positional reference for other catheters and measurements.
The inventors herein have recognized a need for an introducer sheath that will minimize and/or eliminate one or more of the above-identified deficiencies. The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of claim scope.